1. Field of the Invention
This invention relates to the field of tools used in the installation and maintenance of plumbing conduits and pipe, and in particular concerns an improved hand operated tool for temporarily plugging pipe to exclude liquid during a pipe soldering operation or while other work is done on or near the open pipe end.
2. Description of the Prior Art
Many tools are known and used in the plumbing trade for the aforementioned purpose. In general, such tools have a seal element which is introduced into an open end of a pipe to be soldered and is expanded in diameter to make a water tight seal inside the pipe.
The existing tools are cumbersome, costly and require frequent replacement of parts. A continuing need exists for such tooling which is long lasting and safe to operate at low cost.
The present invention addresses the aforementioned need by providing an instrument for temporarily sealing a pipe against fluid flow which has a manually actuatable handle and a sealant unit engaged to the handle. The sealant unit has a seal assembly and a flexible cable operatively connecting the handle and the seal assembly. The seal assembly has a thermoplastic elastomeric seal contained between first and second compression elements along an axial direction of the cable. The thermoplastic elastomeric seal is far longer lasting than other elastomers such as rubber. When rubber seals are exposed to heat, as required in soldering for example, xe2x80x9cdry rottingxe2x80x9d occurs, which drastically reduces the seal life. The seal of the present invention, therefore, reduces replacement costs.
The cable is operative for urging the compression elements together thereby to achieve expansion of the thermoplastic elastomeric seal in a radial direction responsive to manual actuation of the handle from a normal to a depressed condition. Preferably the actuating handle includes locking elements for retaining the handle in a depressed condition when actuated, so that sealing engagement of the seal with the interior surface of a pipe can be maintained without further effort on the part of the user while repair or maintenance work is performed on the pipe.
The actuating handle may have first and second handle members, such as a handgrip and a lever, movable relative to one another from a normal to a depressed condition. The cable may have a sleeve connected at one end thereof to a first handle member and at an opposite end thereof to one of the compression elements, and a wire axially slidable in the sleeve, the wire being connected at one end thereof to a second member of the handle and at an opposite end thereof to another of the compression elements, such that the wire is retracted into the sleeve responsive to relative movement of the handle members. The wire may pass through the first compression element and through the thermoplastic elastomeric seal.
The sleeve is preferably a flexible compressed steel spring to allow maximum flexibility of the cable. Whereas other flexible steel tubing is susceptible to fatigue and fracture upon repeated bending, as through elbows in piping, the compressed steel spring resists such fatigue, thereby increasing the life of the cable.
The cable may alternatively have a sleeve connected at one end thereof to a first handle member and at an opposite end thereof to a connector. This connector is adapted to allow mating engagement of the cable to a modified sealant unit. The modified sealant unit includes a seal assembly and a cable portion. The cable portion is attached to the seal assembly and is further adapted to allow mating engagement between the modified sealant unit and the connector of the cable thereby allowing the user to simply detach the sealant unit from the cable when such becomes desirable. Therefore, the sealant unit may be replaced separately from the cable so that when one or the other becomes worn the entire piece consisting of the cable and sealant unit will not need to be replaced. Due to uneven wear between these two components, this function is highly desirable.
The thermoplastic elastomeric seal element is expanded radially by axial compression of the seal element between the compression elements. In such case the seal element may be axially mounted to the cable. In one embodiment of the invention, the thermoplastic elastomeric seal is expanded by stretching to an increased radius, as by being displaced axially on a tapering surface such as a conical surface. In the latter case, one compression element has the tapering surface and the other compression element urges the seal element along the tapering surface in a direction of increasing width to stretch the seal element. The tapering surface may be a frusto-conical surface coaxial to the cable.
The first element of the handle may be a handgrip and the second element of the handle may be a depressible lever pivoted to the handgrip. The locking elements of the actuating handle may be detent elements on each of the handgrip and the lever engageable with each other upon depression of the lever. The detent elements may operate in the manner of a ratchet, such as a series of teeth on said depressible lever sequentially engageable with a tooth detent on the handgrip during progressive depression of the lever. Desirably, the locking elements will retain the lever against return to a normal condition through a range of depressed conditions until the locking elements are disengaged from each other by the user of the tool.
Safety features are included to protect the user from discomfort resulting from depression of the lever. One such feature is the finger barrier. Upon depression of the lever, a user""s small finger may be pinched between the lower ends of the handgrip and the lever. Moreover, the impact of the lower end of the lever against the small finger of the user upon depression may likewise cause substantial discomfort. Therefore, a finger barrier is provided to protect the small finger of the user from either of these occurrences.
Another safety feature provided is the hand barrier. The hand barrier is provided on the lever to prevent pinching of the portion of the users hand between the index finger and the thumb when utilizing the device.
In one form of the invention the sealant unit is removably engaged to the handle such that different sealant units, each having thermoplastic elastomeric seals of different radial dimension, may be interchangeably engaged to the handle so as to fit a pipe of given standard diameter. Therefore the cable may be disengageable from the handle such that different sealant units each having its own cable and seal assembly may be interchangeably engaged to the handle, so that a tool kit including multiple sealant units each with a seal assembly of different diameter may be provided.
In another form of the invention a modified sealant unit is releasably attached to a cable adapted at both ends to be releasably attachable to the modified sealant unit at one end and the handle at the other end. Therefore, the modified sealant unit can be removed from the handle either alone or in conjunction with the cable.
In yet another form of the invention, the actuating handle may have a third member which is adopted to releasably attach to the cable. The handle may have a channel with a wire section therein connected to a first handle member at one end and the third handle member at the opposite end. Within this channel, an axially disposed spring member may be included to bias the wire toward the third handle member. Therefore, the cable may be releasably attached to the handle quickly and easily.